Method of chilling lubricating oils for dewaxing



EL ELLSBERG Sept. 18, 1934.

METHOD OF CHILLING LUBRICATING OILS FOR DEWAXING Filed Aug. 15. 1951 2 Sheets-Sheet 1 Konin IVEETR BY y E' ATTORNEY7 .T Ztun x55 D .rzunio sept. 18, 1934.

E. ELLSBERG METHOD OF CHILLING LUBRICATING ,OILS FOR DEWAXING Filed Aug. 15. 1931 2 Sheets-Sheet 2 /N VENTO/e A TTORNE y mwm effi-ui mctoQU Paieiiied sept. 1s, 1934 UNITED ,STATESv PArEyjr 'oFFics 1,914,399 Ms'rnon oF emma LUBarcArrNG ons Fon nswAxmG Edward Eusberg, Westfield, N. J., signor or .f -three-fourths to Tide Water Oil Company, y Bayonne, N.J., a corporation of New Jersey Application August 415, "1931, sei-m N0. 557,191 4 (ci. mais) ithas hindern; been. considered that, forv the.-

production of low' cold test cylinder stocks or long residuums obtained from wax-bearing crudea-by the centrifuge method or other. methods," slow-- 5 chilling at a rate of approximatelyf21/2 F. per' hour from the solution point oijthe wax (about 100 F. to 110 F.) down ltothe temperature at which dewaxing is effected, or at this slow chilling rate down to a temperature `of 1.,;.lf,ollowed.by

o somewhat accelerated chilling tothlower.

temperature atwhic -dewaxing occurs 1s essential. to growth of thewax crystal so `that iin-the dewaxing operation itmay be settled, centrifuged, or removed by other dewaxingl methods. j

I have discovered that by proper operation this slow and expensive chilling can be partly or largely eliminated and the dewaxing process greatlyimproved in capacity and decreased in cost.

Contrary to previous practice and theory, my

method consists in taking the mixture of oil to be dewaxed diluted with naphtha, and after heat-` ing to such a point that the wax goes into solution, chilling the solution continuously as 'rapidly as possible to a temperature about one-third to 95 one-half the range through which the solution is;

to be chilled. The oil being thus chilled well below its cloud point, part of the wax is precipitated out of solution. During this process, this oil may be chilled at the rate of 4 F. per minute instead ,30 of 21/2" F. per hour, which is archilling rate completely out of the range of previous practice.

At this point, the partly ahmed ou is removed from the continuous rapid chillers and run continuously through a series of tank chillers, where the chilling rate is much reduced solthat the oil isfurther chilled at a slower rate, about 2-4 F. per hour. During this slower chilling period, suiilcient time is allowed for the gradual growth or formation of wax crystals, so that the oil on T emerging from the chilling system will dewax with the same facility in a' centrifuge plant or other dewaxing method as if the solution had been chilled by the usual slow chilling.

As a result of this method, it is now possible greatly to reduce the time of process, the cost of equipment, and the cost of chilling over methods previously in use. Approximately half the chilling can be done in inexpensive apparatus in a period of ten minutes, which by previous methods required one hundred times that period, or about 18 hours, and a different type of chilling equipment costing six to ten times as much.

The accompanying drawings illustrate schematically an arrangement of apparatus for carrying out the invention, Fig. 1 being a simplified pictorial illustration, and Fig.' 2 being a more diagrammatic illustration omitting some` parts showninFlgJ. v -f The wax-bearing oil andthe -dil/uent are i'ed from tanks 2 and 3, respectivelyfinproper pro- 50 portions, through pipes and 5y to a blending tank 6, where the solution may be heated by means-oi a heating coil?. It will be understood that the' oil in tank '2 may already be partially diluted.V 4The solution ispumped through shock Q5 chillers 8' and then through tank chillers 9, the pipes for this purpose beingmarked loin Fig. l. From the last 'tank chiller, the solution may be pumped through piping 11 direct tov a centrifuge 12, yor `to another'iorm of dewaxing apparatus; 70 or through another branch 13, the solution, after passing through part or all 4oi? the tank chillers, may be put through one or more final shock chillers 88L before going to the dewaxing apparatus.

The dewaxed oil solution is drawn off at 11i and 'U5` the wax at 15; The inlet and outlet connections for passing cooling medium through the various chillers are marked 16 and 1 7 in Fig. 1.

The solution in passage through coils in shook chillers 8 is chilled rapidly from about i00110 80 F. down to about 50 F., for example. Thel so-` lution then passes to theseries of tank (':hiliers 3 comprising as many units as are required. In its slow progress through these tanks and around the cooling tubes therein, the solution is chilled 35 through-the remainder of the chilling range at the vslow rate, and I nd that with my process a rate as high as about 4 F. per hour during this period is not too lfast and permits of additional saving of time and economy in equipment in re- 90 spect to this stage of the process. The solution emerges from the iinal tank chiller at a temperature oi about -50 F. and-is delivered to the dewaxing treatment.' flhe'process is equally effective whetherthe dewaxin'g step is effected by cen- 95 trifuging, by settling, or by filtering.

In Fig. 2 the course of the solution is indicated by the heavy arrowsfwhile the inflow and outiiow of cooling medium is indicated by light arrows. yThe cooling medium may be brine, am-

monia or dewaxedoil.

The invention isznot necessarily limited to chilling at a substantially steady rate throughouta single slow chilling stage succeeding the shockl chilling. and carrying the temperature down "als be accomplished at a rate' of about 4 F. per minute in passage through the additional shock chillers 8a.

I claim:

1, The method which involves heating wax? bearing lubricating oils diluted with lighter hydrocarbons until the wax `goes completely into solution', continuouslyshockchilling the solution Well below the cloud point of the wax, to atemper# ature about temperature through which the solution is to be chilled, then passing they shock-chilled ,solution to a further chilling treatment rate of chilling is radically reduced' to the order: of only a few degrees n tion down to the temperature at" Which-dewa'xing is to occur, after which the chilled solution'is dewaxed. .j l f l 2. The method which involvesheating wax-,- bearing lubricating oils diluted with lighter hydrocarbons until the wax goes completely into solution,v continuously shockl chilling the solution well below the cloud point of the Wax, to a. temperature about one-third to one-hal! the range remesa one-third to one-half the range of.

whereupon ,the

per hour, chillingjthe s olu-` of temperature through which the solution is to be chilled, then passing the shock-chilled solution to a further chilling treatment whereupon the rate of chilling is radically reduced to the order of only a few degrees per hour, gradually chilling the solution to ahoutlQF., and completing the; Vchilling lat an acceleratedf'frata after which the-` chilled solution is'dewax'ed 3. For the dewaxing of wax-bearing lubricat- 'ing oils in solution with lighter hydrocarbons, "the method which comprises chilling the solution yfrom .a.-temparature at which the wax is completelyin solution to a temperature well below I the clcudrpoint oi the wax at a rate on the order ofabout 4f" F. per minute, after which the chill- "ihg Ais conducted 'ata radically reduced rate. 4; For the dewaxing of wax-bearing lubricating oils inl solution with 'lighter hydrocarbons, the methodl which comprises shock chilling the solu- 'tion-fro'mabout 100-110 F., to about 56 F., and effecting further` chilling v at a ,radically reduced 

